E-PROPS MANUFACTURING

1 - Blades

2 - Hubs

3 - Manufacturing process

4 - Balancing

5 - Tracking

The E-Props propellers are fully made in France, in the E-Props workshops, in Provence. The 1700 m² worshops are equiped with 12 CNC machining centers. The company has developed more than 140 propellers models (2018-02-20).

E-Props propellers CARBON range are designed and manufactured to be very light and strong. Materials and manufacturing process have been validated by many tests.

1 - Blades

- made in carbon braid, with continue fibers between upper and lower surfaces of the blade

- epoxy resin

- foam core with internal spar (D-Box)

- blade's foot with titanium ring inside

- 100% carbon, no metallic part = no galvanic corrosion

- internal shielding of the blades : injection at the leading edge of a special resin with Nanostrength® (ARKEMA product : high kinetic energy absorption capacity) => See the page LEADING EDGE PROTECTION

- the epoxy resin is including a high resistance to UV additive (UVA and UVB). Blades are polished with a perfect finition.

- unique ref number on each blade for traceability (RFID chip inside)

The HCF (Helical Continuous Fibers) process, specifically designed by E-PROPS, ensures an exceptional strength of the 100% carbone + epoxy resin blade, from leading edge to trailing edge, from blade's foot to tip.

special high-resistance carbon braid, with thousnads of carbon wires

foam core with internal spar, titanium ring

2 - Hubs

- full carbon + high temperature epoxy resin

- blades and hubs are made in the same material : no problems of interference, no galvaic corrosion

3 - Manufacturing process

Blades and Hub : RTM (Resin Transfer Molding) manufacturing.

This process is used by Airbus for some critical carbon parts on the liner aircraft. It is realized by following a strict cycle of temperatures. The baking of carbon parts allows to improve certain properties, in particular mechanical and of resistance under hot conditions (carbon hubs : max T° resistance = 120°C for reduced engines and 170°C for direct drive engines).

The workshop has three ovens : two medium-temperature / small ovens and a high-temperature / big oven, both managed by computer.

To assure a strict quality control and the reproducibility of the production, the components are exactly weighed very throughout the manufacturing. 15 weighings are necessary for a propeller for Ultralights / Aircraft.

A RFID chip is in each blade is inserted in each blade, with all technical data inside.

E-PROPS ensures the production monitoring by RFID and KANBAN method. These methods and tools optimize the manufacturing quality, reassure and fluidify the supplies, allow the real-time follow-up of the production process, the traceability of all the manufacturing steps, and offer a set of successful and reliable indicators.

E-PROPS : production monitoring by RFID and KANBAN

The E-PROPS team has designed and built from scratch an innovative machining centre to allow the dimensional analysis, the rectification and the finish of the carbon parts automatically, without dismantling of the part. It is equipped with a directional spindle on 5-axis programmed according to the digital definition of the part, with a wide tool store. The precision of measure by the scanner laser is of 5/100th of millimeter.
The scanner sweeps the carbon part, the program recognizes it according to ts database, then the different tools come to make all the finishing work: deburring, cut, drilling, sanding and polishing. All the stages between the molds and the stock are automatic.

4 - Balancing

The E-Props propellers are precisely balanced, if possible with their accessories (spinners).

The team is using an electronic bench to balance the propellers, with 2 oscilloscopes.

The maximum tolerance accepted is 0,3 gr/m

E-Props propellers are well known to generate very few vibrations, due to their very light weight and to their very precise balancing.

Be careful : the blades have not necessarily the same weight.

To balance a propeller, the weight of both blades is important, of course, but before all the weight distribution all along the blade.

Example :

The weights P1 et P2 of each blade apply respectively to centre of gravity G1 and G2, which are not at an equal distance on the center of rotation O of the propeller.

The balancing must be realized to obtain : P1 x d1 = P2 x d2

It is strongly discouraged to add weight to one blade, in order to have the same weight for all blades. The propeller would be then unbalanced, and can cause some vibrations.

In case of doubts, il is possible to returm the propeller to E-Props for balancing verification. Please contact us : helices@e-props.fr

When the propellers are light, good balanced with a very low tolerance, a static balancing is enough to avoid vibrations perception and vibrations consequences. In this case a dynamic balancing is not necessary.

5 - Tracking

Propeller track is the path followed by a blade segment in one rotation.

E-Props have flexible blades. The maximum tracking is 10 mm.

PROPELLERS FOR PARAMOTORS :

Do not put a rubber washer between the propeller and the reducer flange to reduce the tracking.

It is dangereous because the loads are transferred to the propellers screws and those screws can suddenly break.